One method for testing electrical circuits is already known from German Patent Disclosure Document DE-OS 36 32 569 and the corresponding U.S. Pat. No. 4,839,812, NUSSER et al. Therein, the individual inputs and outputs of the control unit are tested separately in individual test steps. This is accomplished with a simulation and measuring unit, which provides specific signals to the inputs of the control unit. These signals are then retrieved by a test program stored in the memory of the control unit. Controlled by the test computer connected to the simulation and measuring unit, the data determined by the test program are then transferred to this test computer and checked for accuracy. If necessary, the test computer initiates an error message. The test computer also applies certain data to the control unit via the interface and commands the control unit to transfer these data to certain outputs. With the measuring instruments, contained in the simulation and measuring unit, the test computer checks these data for accuracy. If the values are not within a predetermined command value range, the test computer will initiate an error message.
Application of this test method is very time-consuming because the individual inputs and outputs have to be tested separately and a certain waiting period has to elapse before processing a test step by the test program. During this time, the test computer can apply other data to the inputs.